Epstein-Barr virus is a unique human pathogen because of its ability to stimulate proliferation and immunoglobulin synthesis by normal human B lymphocytes. This biologic property underlies the association of the virus with a number of benign and malignant lymphoproliferative diseases, and makes it a likely candidate for involvement with autoimmune diseases as well. The present program represents the efforts of a group of closely collaborative, interdependent investigators who are taking advantage of remarkable technical advances in molecular biology in order to provide a better understanding of the epidemiology, clinical spectrum, diagnosis and pathogenesis of EB virus infections. Among the problems to be addressed are: 1) the use of cloned genes as tools in seroepidemiology, 2) the relationship of small EBV encoded RNA's to the pathogenesis of systemic lupus and Sjogren's syndrome, 3) rapid viral diagnosis by means of "spot blots", 4) production of human monoclonal antibodies to heterophile and autoimmune antigens, 5) mechanisms of lymphocyte immortalization by EBV, 6) regulation of expression of EBV early genes, 7) function of small RNA's and 8) improved methods of labelling nucleotides to be used as probes for the location and expression of viral genomes.